Many types of integrated circuit chips utilize wire bonding to electrically connect the circuit contained in the chip to the next higher level of packaging. Wire bonding involves forming bond pads at the periphery of the chip, and bonding an end of a respective wire to each one of the bond pads. The other end of each respective wire is connected to a contact on the next higher level of packaging. The bond pads are typically composed of aluminum, and the wires are typically composed of gold or copper.
Gold or copper wire bonding to an aluminum bond pad often creates aluminum ‘splash’ as a result of the ultrasonic scrubbing operation that is used to form the permanent bond between the wire and the bond pad. Copper wire bonding offers a cost-effective alternative to traditional gold wire bonding, but has an enhanced tendency to splash due to higher forces required during bonding.
Thus, with copper (Cu) wire bonding the splash concern drives the aluminum bond pad size to be larger than it would otherwise be for gold wire bonding. A metal splash defect creates a foreign material defect concern and can, in some cases, result in metal bridging causing electrical shorts between adjacent metal bond pads or between a bond pad and an adjacent wire. Metal splash has been observed on fabricated parts with sufficient size and density to suggest the potential for metal-to-metal shorting (e.g., shorting between adjacent bond pads).
Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove.